[MACHINE GOAT]

Any one here experienced welding 4140? We have been welding 4140 for decades and still have chronic problems with cracking welds. Some jobs just
seem posessed by a crack poltergeist. We weld pre-heat treated material and sometimes annealed and then send to heat treat. We have been using er70s6
filler rod. Any advice appreciated.

Eric

[mcarvey]

I don't have tons of experience welding 4140 but do consider myself fairly knowledgeable about the metallurgical properties of steel. Could you give us some more information about the problems you are having? What is the thickness of the parts that you are welding? What kind of welding are you using (MIG/TIG/Stick/torch?) Are you doing any pre-heating of the metal? Are the parts cracking before or after heat treatment? What kind of heat treatment process are you using? What is your final desired rockwell hardness?

-Matt

[kccrusher]

I would check the rod you are using, as it is diluting the parent metals composition. I would drop the ER70S6 and go with Oxweld #32CMS or similar. We use it on our 4130 weldments and it's heat treatable. I would also check the cool down rate post welding, as you know, if it cools rapidly, part cracking can develop. On a lot of our parts with varying cross sections, etc. they are wrapped in heat blankets to prevent airflow from cooling them too quickly.